Functional fluid compositions

ABSTRACT

Functional fluid compositions particularly useful as hydraulic fluids comprising as base stocks dihalogenated diphenyl ethers or sulfides and as blending agents halogenated lower alkylbenzenes, monohalogenated diphenyl ethers, halogenated benzenes and chlorinated biphenyls or combinations thereof.

United States Patent Nowotny et al.

[ 1 Feb. 22, 1972 FUNCTIONAL FLUID COMPOSITIONS Kurt A. Nowotny, Dublin, Califi; Robert W. Street, Bloomington, Incl.

Assignee: Monsanto Company, St. Louis, Mo.

Filed: Nov. 14, 1967 Appl. No.: 682,980

Related US. Application Data Continuation-impart of Ser. No. 398,080, Sept. 21, 1964, abandoned.

Inventors:

US. Cl ..252/78, 252/73, 252/77 Int. Cl. ..C09k 3/02 Field of Search ..252/77, 78, 73, 54, 52, 48.8;

References Cited UNITED STATES PATENTS 5/1966 Gundelson ..252/49.6

Primary Examiner-Leon D. Rosdol Assistant Examiner-P. E. Willis AttorneyNeal E. Willis and J. E Maurer [57] ABSTRACT Functional fluid compositions particularly useful as hydraulic fluids comprising as base stocks dihalogenated diphenyl ethers or sulfides and as blending agents halogenated lower alkylbenzenes, monohalogenated diphenyl ethers, halogenated benzenes and chlorinated biphenyls or combinations thereof.

5 Claims, No Drawings FUNCTIONAL FLUID COMPOSITIONS This application is a continuation-in-part of copending application, Ser. No. 398,080, filed Sept. 21, 1964 now abandoned.

This invention relates to novel functional fluid compositions comprising as base stocks dihalogenated diphenyl ethers or sulfides and as blending agents therewith halogenated lower alkylbenzenes, monohalogenated diphenyl ethers, halogenated benzenes or chlorinated biphenyls or combinations thereof. Wherever the term halogen" or halogenated or the like is used herein, only bromine and chlorine are contemplated.

Many different types of materials are utilized as functional fluids and functional fluids are used in many different types of applications. Such fluids have been used as electronic coolants, atomic reactor coolants, diffusion pump fluids, synthetic lubricants, damping fluids, bases for greases, force transmission fluids (hydraulic fluids) and as filter mediums for air conditioning systems. Because of the wide variety of applications and the varied conditions under which functional fluids are utilized, the properties desired in a good functional fluid necessarily vary with the particular application in which it is to be utilized with each individual application requiring a functional fluid having a specific class of properties.

Of the foregoing, the use of functional fluids as hydraulic fluids, particularly aircraft hydraulic fluids, has posed what is probably the most difficult area of application. Thus, up to a few years ago the requirements for an aircraft hydraulic fluid could be described as follows:

The hydraulic power systems of aircraft for operating various mechanisms of an airplane impose stringent requirements on the hydraulic fluid used. Not only must the hydraulic fluid for aircraft meet stringentfunctional and use requirements but in addition such fluid should be as highly nonflammable as possible and must be sufficiently nonflammable to satisfy aircraft requirements for fire resistance. The viscosity characteristics of the fluid must be such that it may be used over a wide temperature range; that is, adequately high viscosity at high temperature, low viscosity at low temperature and a low rate of change of viscosity with temperature. Such temperature range is generally from 40 to 250 F. Its pour point should be low. Its volatility should be low at elevated temperatures of use and the volatility should be balanced; that is, selective evaporation or volatilization of an important component should not take place at the high temperatures of use. it must possess sufficient lubricity and mechanical stability to enable it to be used in the self-lubricated pumps, valves, etc., employed in the hydraulic systems of aircraft which are exceedingly severe on the fluid used. it should be thermally and chemically stable in order to resist oxidation and decomposition so that it will remain uniform under conditions of use and be able to resist the loss of desired characteristics due to high and sudden changes of pressure and temperature, high shearing stresses, and contact with various metals which may be, for example, aluminum, bronze, copper and steel. It should also not deteriorate the gaskets or packings of the hydraulic system. it must not adversely affect the materials of which the system is constructed, and in the event of a leak, should not adversely affect the various parts of the airplane with which it may accidentally come in contact, such as electrical wire insulation and paint. it should not be toxic or harmful to personnel who may come in contact with it.

While it is evident that the aforementioned requirements are quite severe, the development of the commercial supersonic transport (SST) has imposed requirements on any hydraulic fluid to be used therein which make the satisfaction of such prior requirements appear to be no problem at all.

in the first place, the SST flight control system will be more difficult to design than that of any current commercial aircraft since it must have excellent flight control characteristics both at subsonic and supersonic speeds. It is estimated that the SST, a Mach 3 aircraft, will spend approximately half its time at the climb, hold, and approach conditions. Further, if past and current trends are any indication, it can be assumed that the SST hydraulic functions will be somewhat more numerous than those of current commercial jets. Indications are that the commercial SST will have about 1,000 hydraulic horsepower. This extended horsepower demand, needed to drive accessories, landing gear, and the control system, of itself will impose severe reliability considerations on the hydraulic fluid. Coupled to the factor of component numbers versus reliability is the factor of higher temperatures to which the system will be subjected. Surface temperatures of a Mach 3 aircraft will range from 450 to 600 F. or higher at stagnation points. By taking advantage of natural heat sinks, such as the fuel in a manner utilized in the 8-70, the hydraulic system should be capable of performing with a fluid operating at 400 to 500 F. On the other end of the temperature scale, temperatures as low as 40 F. are anticipated.

The Commercial Jet Hydraulics Panel of SAE A6, which was initiated during 1961 for the purpose of investigating and making recommendations for corrections of current fire-resistant jet hydraulic systems, found that two-thirds of all hydraulic system incidents during a lie-year period prior to June 1962 were due to external system leakage, largely from components such as lines, fittings, hoses and seals. This leakage problem was considered by the panel and industry in general to be a very undesirable situation from the standpoint of loss of powered control. In the SST, any leakage problems would be magnified excessively over and above the loss of powered control when one considers the temperatures involved. In this case, there is no longer the situation in which leakage fluid will issue into relatively cold areas but rather into ambient temperatures as high as 600 F. It is apparent that a flammable fluid injected into hot compartments would create a blowtorch effect, an untenable condition. A fire-resistant fluid is thus of greater importance than ever before.

The principal problem facing a fluid supplier, therefore, is that of developing an SST fluid having temperature compatibility to approximately 400 to 500 F. combined with fire resistance. In addition to the foregoing an SST hydraulic fluid must still have the properties mentioned above, including good viscosity characteristics (over a quite extended temperature range), a low freezing point, low volatility, sufficient lubricity, no toxicity and compatibility with various metals, packings and gaskets.

Based upon the specifications of the various SST airframe manufacturers, the requirements for a hydraulic fluid for the SST and similar supersonic aircraft are expected to be as follows:

[SST hydraulic fluid requirements] Property Requirement Viscosity:

40 F 4,000 cs. or less. 400F 0.5 cs. or more. crystallizing point -50 F. minimum. Thermal stability: 500 F.

(isoteniseope) ire resistance:

Molten aluminum test Does not ignite without spark.

Self-extinguishing with spark.

Does not burn on leaving tube or in the pan.

High pressure spray test Does not flash up to 5 feet from orifice.

(AMS 3,160 0. plus No.4 tip). Can flash beyond 5 feet but is selfextinguishing, Volatility 3.1. 500 F. Autogenous ignition 1,000 F.

temperature.

While the SST requirements set forth above may not appear to be difficult to meet, these requirements are in fact quite severe for many reasons. For example, there are few, if any, individual compounds known which remain usable over the extreme temperature range of at least 550 F. (i.e., from 50 F. crystallizing point to 500 F. thermal stability) much less provide such a usable range, be fire resistant and also have the desired viscosities.

it is, therefore, an object of this invention to provide functional fluid compositions having a combination of properties,

such as wide liquid range and fire resistance, which make such compositions well suited for the various applications mentioned above. It is a further object of this invention to provide functional fluid compositions which are useful as hydraulic fluids, particularly aircraft hydraulic fluids. A further a to provide functional fluids useful as hydraulic fluids i ri diipei sonic aircraft.

Other objects will be apparent from the following description of the invention.

It has now been found that functional fluids having excellent fire resistance coupled with the physical properties necessary to provide compositions useful for the many applications disclosed above and particularly as aircraft hydraulic fluids comprise (A) a base stock selected from certain dihalogenated diphenyl ethers or sulfides and (B) a blending agent selected from I, (l) halogenated lower alkyl benzenes (2) monohalogenated diphenyl ethers (3) halogenated benzenes and (4) chlorinated biphenyl and II any combination of l) to (4) wherein blending agent (8)] is present in the weight range of from about 10 to about 50 parts per 100 parts (A) and blending agent of (B)Il is present in the weight range of from about 10 to about 200 parts per 100 parts of (A).

Accordingly, compositions of this invention comprise a base stock (A) above in a major amount and minor amounts of certain blending agents (B). Thus in compositions of this invention when only one blending agent (B)l, is employed, its concentration is in the range of from about 10 to about 50 parts, by weight, per 100 parts, by weight of base stock (A). Preferably the amount of blending agent (B)l is in the range of from about to about 35 parts, by weight, per 100 parts of base stock (A). When, a combination of blending agents is employed, the total amount of all blending agents, (3) above, can exceed the amount of base stock (A) by as much as a 2 to l weight ratio. It is preferred to employ from about to about 175 parts, by weight, of blending agent (B)ll per 100 parts, by weight, of base stock (A). in most instances the amount, by weight, of any single blending agent (B)I (l)-(4) above will not exceed the amount of base stock (A) in the composition.

The dihalogenated diphenyl ethers suitable for use as base stocks in the fluid compositions of this invention are those represented by the structure where A is oxygen or sulfur and X and Y are bromine or chlorine.

Typical examples of such ethers and sulfides are 1. different halogen on each ring:

chlorodiphenyl sulfide. 2. same halogen on each ring: 2,2'-dibromodiphenyl ether, 2,2'-dibromodiphenyl sulfide, 2,3 '-dibromodiphenyl ether, 2,3 -dibromodiphenyl sulfide, 2,4'-dibromodiphenyl ether, 2,4-dibromodiphenyl sulfide,

chlorodiphenyl 3,3 -dibromodiphenyl ether, 3,3 '-dibromodiphenyl sulfide, 3,4'-dibromodiphenyl ether, 3,4-dibromodiphenyl sulfide, 4,4'-dibromodiphenyl ether, 4,4'-dibromodiphenyl sulfide, 2,2-dichlorodiphenyl ether, 2,2'-dichlorodiphenyl sulfide, 2,3'-dichlorodiphenyl ether, 2,3-dichlorodiphenyl sulfide, 2,4'-dichlorodiphenyl ether, 2,4'-dichlorodiphenyl sulfide, 3,3'-dichlorodiphenyl ether, 3,3-dichlorodiphenyl sulfide, 3,4'-dichlorodiphenyl ether, 3,4'-dichlorodiphenyl sulfide, 4,4'-dichlorodiphenyl ether and 4,4'-dichlorodiphenyl sulfide.

The ethers are generally preferred over the sulfides because their lower melting points make them usable in a wider number of applications and of the ethers, those in which the halogen substituents are in the 3,4'-relationship are preferred for use in the compositions of this invention, because their low melting points are the lowest of all the base stocks of the instant invention.

The blending agents which can be used to provide the novel compositions of this invention include the halogenated lower alkyl (C,.,) benzenes containing one to five halogens, such as 4-bromomethylbenzene, 2-bromoethylbenzene, 4-bromopropylbenzene, 4-chlorobutylbenzene, 2,4-dichloromethylbenzene, 2,3-dibromoethylbenzene, 2,4-dibromoethylbenzene, 2,4-dichloroethylbenzene, 2-bromo-4-chloroethylbenzene, 2,5dibromoethylbenzene, benzene, 3,S-dibromopropylbenzene, 2,4-dichlorobutylbenzene, and the like. It is preferred to use the bromine-containing compounds because of the increased fire resistance obtained thereby. Further examples of halogenated alkyl benzenes are triand tetrachloroethylbenzene, triand tetrabromoethylbenzene, pentachloromethylbenzene, pentachloroethylbenzene, pentabromoethylbenzene, pentabromopropylbenzene, pentachlorobutylbenzene and the like.

The halogenated benzenes which can be used as blending agents include chloroand bromobenzenes. The preferred chlorobenzenes are di-, triand tetrachlorobenzene and mixtures thereof. The preferred bromobenzenes are mono-, di-, and tribromobenzene and more particularly mdibromobenzene. Typical examples of halogenated benzenes useful as blending agents are o-dichlorobenzene, mdichlorobenzene, 1,2,3-trichlorobenzene, 1,2,4- trichlorobenzene, 1,2,3 ,S-tetrachlorobenzene, odibromobenzene and 1,2,4-tribromobenzene.

In addition to the use of specific compounds, there can be used a mixture of halogenated alkyl benzenes such as the mixture of brominated ethyl benzenes disclosed in U.S. Pat. No. 2,257,903, which contain an average of two atoms of bromine per mol of ethyl benzene. The mixture of Example 1 of U.S. Pat. No. 2,257,903 is particularly preferred for use in the fluids of this invention because of its low crystallizing point.

Other blending agents include the monohalogenated diphenyl ethers such as 2-chlorodiphenyl ether, 3- ether, 4-chlorodiphenyl ether, 3- bromodiphenyl ether and the like and chlorinated diphenyl which is illustrated by the chlorinated biphenyl commercially available as products containing about 21%, 32%, 42%, 48%, 54% and 60% of combined chlorine corresponding approximately to mono-, di-, tri-, tetra-, pentaand hexachlorobiphenyl, respectively. The expression chlorinated biphenyl containing a stated percentage of combined chlorine is used herein as not only including these directly chlorinated products, but also as blends of one or more chlorinated biphenyl whereby the total chlorine content is broadly within the range of 20 to 60 percent, preferably within the range of 20 to 42 percent by weight, It is also preferred, in order to obtain fluids having low crystallizing points, to use chlorinated biphenyl which has been isomerized and preferably distilled thereafter according to the teachings of U.S. Pat. No. 3,068,297.

The preparation of the base stock compounds used to provide the compositions of this invention is illustrated by the following examples in which parts are parts by weight.

3,4-dibromoethyl- EXAMPLE 1 charged 610 parts of 3-chlorodiphenyl ether and 2 parts of 5 powdered iron. The resulting mixture is heated to about 65 C. followed by the slow addition of 320 parts of liquid bromine. During the addition of bromine the reaction mass is maintained at 6080 C. After completing the addition of bromine the reaction mass is slowly heated to about 135 C. and then held at that temperature for 4 hours. The pressure in the reaction system is then lowered to about 100-200 mm. of Hg. and maintained for about 30 minutes in order to remove as much residual hydrogen bromine as possible. After cooling the reaction mixture to about 70 C., parts of calcium oxide is charged and the resulting mixture is fractionated to give a main fraction containing 4-bromo-3:-chlorodiphenyl ether and a small amount of the other isomers such as the 3,3:- isorner. The product is a colorless liquid having an index of refraction, n of 1.6128, a specific gravity of 1.485 and a boiling range of l48l58 C. at 1.0 mm. of Hg.

Alternatively the mixed halogen-containing diphenyl ethers can be prepared by the Ullman reaction. Although this method yields the desired product in pure form, it is a somewhat expensive procedure and is, therefore, not as commercially attractive, especially since the procedure illustrated in Example 1 yields a mixture having of the order of 90 percent of the desired product which mixture is quite useful in the instant invention. The sulfides can be prepared by reacting an alkali metal halothiophenolate with a dihalobenzene in a carboxamide or N-alkyl pyrrolidone. An example of the preparation of a base stock compound of this invention by the Ullman reaction is given below.

EXAMPLE 2 Into a suitable reaction vessel there is charged 212.1 parts of m-chlorophenol and 84.2 parts of potassium hydroxide followed by the addition of 150 ml. of toluene. The resulting mixture is heated to complete formation of the potassium chlorophenolate while removing, azeotropically, 34 ml. of I water. The toluene is then stripped and 500 ml. of diglyme is added. There is then charged to a different reaction vessel 707.7 parts of p-dibromobenzene, 5 parts of cuprous chloride and 3 parts of potassium iodide. The resulting mixture is heated to 165 C. and then the phenolate previously prepared is slowly charged over about 1% hours. After completing the phenolate addition, the reaction mass is held at 165 C. for an additional 5 hours. The diglyme is then stripped and the residue diluted with ether and filtered, washed with 10 percent caustic solution and water and dried. The purified residue is then fractionated to provide the desired 4-bromo-3'- chlorodiphenyl ether which has a boiling point of 130 C. at 0.4 mm. of Hg., a crystallizing point of 8 F. and an index of refraction, n,, of 1.6138.

EXAMPLE 3 Into a suitable reaction vessel containing 944 parts of mdibromobenzene there was slowly charged a solution of potassium phenate in diglyme (prepared by dissolving 122 parts of potassium hydroxide in 257.1 parts of p-chlorophenol and removing the water formed by distillation using toluene), 6 parts of cuprous chloride and 4 parts of potassium iodide. The resulting mixture was heated at 165 C., with agitation, for about 5 hours after which the diglyme was removed by distillation by heating the mixture at reduced pressure. The residue remaining was then taken up in ether and the solids removed by filtration. The ether solution was then washed with 10 percent caustic solution followed by washing with water, and dried. The ether was then evaporated and the residue fractionated to give the desired product, 3-bromo-4'- chlorodiphenyl ether, which had a boiling range of 128 C. at 0.2 mm. of Hg, a melting point of 7 F. (14 C.) and an index ofrefraction, u of 1.6130.

EXAMPLE 4 In the manner of Example 3, the potassium salt of mchlorophenol was reacted with pdichlorobenzene to provide 3,4-dichlorodiphenyl ether which had a boiling point of 1 13 C. at 0.5 mm. of Hg., a melting point of 14 F. (10 C.) and an index of refraction, u of 1.5950.

EXAMPLE 5 Into a suitable reaction vessel there was charged 289.3 parts of p-chlorothiophenol, 944 parts of m-dibromobenzene and 200 ml. of N-methylpyrrolidone and the resulting mixture was heated to C. There was then charged 123.4 parts of potassium hydroxide in 500 ml. of ethanol after which the reaction mixture was heated at reflux for about 1 1 hours. The reaction mass was then cooled, taken up in ether and filtered. The filtrate was washed with dilute caustic solution, then with water, and dried. The residue was then fractionated to provide 3-bromo-4-chlorodiphenyl sulfide which had a boiling point 00141? C. at 0.2 mm. of l lg a n el ting point of 104 F. (40

0. andan index of refraction, n of 1.6608.

EXAMPLE 6 In the manner of Example 5, 147 parts of pchlorothiophenol, 441 parts of m-dichlorobenzene and 56.1 parts of potassium hydroxide were reacted in N-methylpyrrolidone to provide 3,4-dichlorodiphenyl sulfide which had a boiling point of 127 C. at 0.4 mm. of Hg., a melting point of 86 F. (30 C.) and an index of refraction, n,, of 1.6454.

Other base stock compounds of this invention can be similarly prepared. Typical properties of the above-prepared and other base stock compounds of this invention are set forth in Table 1, below. The tests or procedures used to measure the various properties of the fluids of this invention and the components thereof are as follows:

Viscosity ASTM D44S-6l Hot Manifold Test AMS 3150C High Pressure Spray Test AMS 3150C Autogenous ignition Temperature ASTM D-2155-63T In addition, the solution or melting point of the compositions of this invention were also measured. Because the compositions of this invention were also measured. Because the compositions of the instant invention easily supercool (as do the components) crystallizing points are difficult to determine. However, since solution point and crystallizing point coincide the solution point was generally measured.

Solution points were determined by placing a test composition in a test tube provided with an agitator and suspending the apparatus in a well insulated dry ice, acetone bath. The dry ice, acetone bath was maintained at a temperature in the range of 30 to 50 F., a range considered high enough to prevent a glass from forming and low enough to speed up potential crystallization. After a test composition had been agitated for about 8 hours, seeds of one of the components were added. The seeded composition was then stored in a cold box at 50 F. for 16 hours and then agitated in the dry ice, acetone bath for 8 hours. The cycle was then repeated. Those mixtures which did not crystallize after 1 week were warmed to room temperature to make the fluids pourable and transferred to small bottles with lids. The bottles were then placed in cold storage at 60 F. In either case, upon the inducement of crystallization, the container was heated gradually with agitation and the temperature noted at which the last crystal dissolved. Using the aforedescribed tests and procedures, properties of various compounds utilized herein were determined and such properties are set forth in Table 1, below.

The thermal stability of the components and compositions of this invention were determined by the use of an isoteniscope according to the procedure of Blake et al., J. Chem. Eng. Data, 6, 87 (1961). When a fluid is heated in the isoteniscope apparatus, it exerts a vapor pressure which can be readily measured. The vapor pressure increases as tem- TABLE 1 Solution Boiling Thermal Viscosity, es.

point, point, stability,

Compound F. F. Tn, F. F. 100 F. 210 F. Molten metal test 3,3-dichlorodiphenyl ether 54 596 784 1,972 3.77 1.27 Does not ignite spontaneously. ignites with spark and burns to completion.

3,3-dibromodiphenyl ether 82.4 670 648 6.10 1.60 Does not ignite spontaneously. Flashes with spark. Does not burn to completion.

4,4-dibromodiphenyl ether 141 666 667 1. 60 Do.

4-br0mo3-chlorodiphenyl ether 8 640 639 11,680 4.37 1.46 Does not flash without a spark. Flashes with spark and is immediately seliwxtingnishing.

3-bromo-3-chlorodiphenyl ether..." 63 660 4.66 1.40 Does not ignite without spark. Flashes with spark but is seIfeXtinguishing.

3-bromo-4'-chlorodiphenyl ether 7 650 4. 93 1. 46 Do.

3,3-dibromodiphenyl sulfide 100 648 7.92 1.91 Does not ignite with spark. Flashes with spark.

Does not burn to completion.

3,3-dichlorodiphenyl sulfide 67 656 718 2, 320 4.55 1.47 Does not ignite spontaneously. Flashes with spark. Does not burn to completion.

3-bromo-4-chlorodiphenyi sulfide. 104 720 1.66 Does not ignite without spark. Flashes with spark but is self-extinguishing.

3,4-dichlorodiphenyl su1fide 86 660 2. 040 4. 30 1. 46 Do.

2,2-dichlorodipheny1 ether 207,11}? 6.97 1.68

2,3-dichlorodiphenyl ether 19, 630 5. 18 1. 47

2,4-dichlorodlphenyl ether 88 18, 250 4. 83 1. 42

3,4-dichlorodiphenyl ether 610 1,530

4,4'-diehlorodiphenyl ether perature is increased following a straight line relationship when logarithm of pressure is plotted versus the reciprocal of the absolute temperature. The vapor pressure curve will depart from a straight line if decomposition occurs to give volatile products. The temperature at which this occurs is called the decomposition temperature (T Several tests were used for the measurement of the fire resistance of the instant fluids since there is no single test that can be used to evaluate all types of fluids under all expected use conditions. The degree of fire resistance in any given test is influenced by the characteristics of the fluid, the type of flame or source of ignition, the total amount of energy available in relation to the amount of fluid, the physical state of the fluid, and many other factors.

The early technical committees working on fire-resistant hydraulic fluid specifications for aircraft recognized the many factors involved in assessing fire resistance. As a result, the specifications developed by the SAE and the military required several different methods for testing the flammability of proposed products.

These specifications include the same general type of fireresistance tests. The tests were designed to simulate conditions in aircraft resulting from a broken line spraying hydraulic fluid into various sources of ignition and are known as the High-Pressure Spray Test," and the Hot Manifold Test. An additional test often used, which is a smaller scale test, is the Molten-Metal Pour Test. In this test the fluid under evaluation is dropped from a medicine dropper or poured from a calibrated test tube onto the surface of molten aluminum alloy which has been heated to about l,250 F. If spontaneous ignition does not occur, a flame is placed in the vapors to determine ifthey can be ignited. I

From the properties set forth in Table i above, it is evident that the base stock compounds have a combination of physical properties which make them well suited for use as functional fluids, yet in most cases they are deficient with respect to some property which limits their commercial applicability. The

problem to which the present invention is directed, therefore, is to provide functional fluids having the combination of properties discussed above and which, therefore, retain the good; fire resistance of the base stocks yet are improved with respect to one or more other properties, such as lowor high-temperature viscosity or solution point. The problem can also be. stated, in the case of those base stocks not having the desired fire resistance, of improving their fire resistance without ad-. versely affecting viscosity and thermal stability and to also obtain fluids having good low-temperature properties.

Representative properties of typical blending agents used in the compositions of this invention are set forth in Table ll. (See col. 9.)

The deficiencies of the aforedescribed base stock compounds of this invention are significantly improved by the addition of such compounds of the above-described blending agents to thereby provide the compositions of the instant invention, typical examples of which and their properties are LEKQQLQTM 99%...

Similarly compositions of this invention can be based on the use of a dihalodiphenyl sulfide instead of a dihalodiphenyl ether. Typical examples of such compositions are set forth below in Table IV.

The compositions of this invention also possess good lubricating properties as evidenced by the results obtained from testing of such compositions on the four-ball machine. Typical results are listed in Table V below. The composition numbers are for the compositions listed in Table III.

TABLE V Scar diameter, mm.

Temper- Steel on Steel on Composition No. ature steel bronze NOTE-Test conditions: 40 kg., 1,200 r.p.m. for 1 hour at the temperature indicated.

in addition to the above the compositions of this invention are shear stable and are not prone to foaming and any foam formed is not stable. Furthermore, the claimed compositions have good stability, even at temperatures of 550 F. and in the presence of oxygen, and are essentially noncorrosive to metals, such as aluminum, aluminum bronze. iron, silver and titanium. A further advantage of the instant compositions is their outstanding hydrolytic stability.

Other compositions of this invention are listed below in Table Vl wherein parts are parts by weight.

TABLE VI Composition Parts by No. Components weight 3-bromo-4'-ehlorodiphenyl ether. 100 5 B-chlorodlphenyl ether 60 m-Dibromobenzene 6O 3,3-dichlorodlphenyl ether. 100 6 Chlorinated biphenyl32% 01.. 25 m-Dlbromobenzene 76 7 3-bromo-3-chlorodiphenyl ether- 100 Bromoethyl ethyl benzene 8 {3,3-dlbro1n0dlphenyl ether 100 Dibromoethyl benzene 60 9 {3,3-dlchlorodlphenyl sulfide 100 3-chlorophenyl phenyl ether 10 {3-bromo-4'-chlorodlphenyl sulfide- 100 Dlbromoethyl benzene 10 u 4,4-dibron1odiphenyl ethen. 100 m-Dibromobenzene 60 12 {3.4-dlchlorodiphenyl sulfide 100 Chlorinated blphenyl42% CL... 10 3-bromo-4-chlorodlphenyl ether- 100 m-Dibromobenzene 50 13 Chlorinated biphenyl21% Cl 50 Bromoethylbenzene.. 3-bromopheny1 phenyl ether- 50 3-chlorodlphenyl ether 25 3-bromo-4-chlorodiphenyl sulfide. 100 14 3-chlorodiphenyl ether 100 Chlorinated biphenyl32% Cl 100 3,4-diehlorodiphenyl sulfide 100 15 Bromophenyl phenyl ether- 5 m-Dibromobenzene 5 4-bromo-3-chlorodlphenyl ether 100 16 3-bro1nophenyl phenyl ether 1O m-Dibromobenzene 20 As a result of the excellent physical properties of the functional fluids particularly described in the preceding examples, improved hydraulic pressure devices can be prepared in accordance with this invention which comprise in combination a fluid chamber and an actuating fluid in said chamber, said fluid comprising a mixture of one or more of the base stocks hereinbefore described. In such a hydraulic apparatus wherein a movable member is actuated by the above-described functional fluids, performance characteristics are obtainable which are superior to those heretobefore obtainable.

Because of the excellent fire resistance of the functional fluids of this invention, their exceptionally low pour points, and good lubricity, the functional fluids of this invention can be utilized in those hydraulic systems wherein power must be transmitted and the frictional parts of the system lubricated by the hydraulic fluid utilized. Thus, the novel functional fluids of this invention find utility in the transmission of power in a hydraulic system having a pump therein supplying the power for the system. In such a system, the parts which are so lubricated include the frictional surfaces of the source of power, namely the pump, valves, operating pistons and cylinders, fluid motors, and in some cases, for machine tools, the ways, tables and slides. The hydraulic system may be of either the constant-volume or the variable-volume type of system.

The pumps may be of various types, including the pistontype pump, more particularly the variable-stroke piston pump,

the variable-discharge or variable displacement piston pump, radial-piston pump, axial-piston pump, in which a pivoted cylinder block is adjusted at various angles with the piston assembly, for example, the Vickers Axial-Piston Pump, or in which the mechanism which drives the pistons is set at an angle adjustable with the cylinder block; gear-type pump, which may be spur, helical or herringbone gears, variations of internal gears, or a screw pump; or vane pumps. The valves may be stop valves, reversing valves, pilot valves, throttling valves, sequence valves or relief valves. Fluid motors are usually constantor variable-discharge piston pumps caused to rotate by the pressure of the hydraulic fluid of the system with the power supplied by the pump power source. Such a hydraulic motor may be used in connection with a variabledischarge pump to form a variable-speed transmission.

it is interesting to note that the base stock compounds of this invention which contain one bromine atom and one chlorine atom possess a unique combination of fire resistance and viscosity. Thus, such compounds are as fire resistant or have the ability to impart as much fire resistance as chlorinated diphenyl ethers and sulfides containing at least three chlorine atoms but do not suffer from the problems of having the high viscosities at low temperatures which is common to such trichlorinated compounds and which problem is further magnified with compounds containing more than three chlorines. The chlorineand bromine-containing compounds are, therefore, preferred moieties of the instant invention because such combination of fire resistance and good lowtemperature viscosities malce them particularly well suited for .use in hydraulic fluid formulations where wide variations in temperature are likely to be encountered.

The compositions of this invention can also contain dyes, pour point depressants, antioxidants, viscosity index improvers, such as polyalkylacrylates and polyalkylmethacrylates, lubricity agents and the like.

While this invention has been described with respect to various specific examples and embodiments, it is to be understood that the invention is not limited thereto and that it can be variously practiced within the scope of the following claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A composition consisting essentially of A. 4-bromo-3'-chlorodiphenyl ether and B. from about 10 to about 50 parts by weight of a monohalogenated diphenyl ether wherein the halogen is bromine or chlorine, per parts by weight of said 4- bromo-3 '-chlorodiphenyl ether. 2. A composition of claim 1 where the monohalogenated diphenyl ether is 3-chlorodiphenyl ether.

3. A composition of claim 1 where the monohalogenated diphenyl ether is 3-bromodiphenyl ether.

4. A composition consisting essentially of 4-bromo-3'- chlorodiphenyl ether and 3-chlorodiphenyl ether wherein said 3-chlorodiphenyl ether is present in amounts of from about 17 to about 33 parts by weight per l00 parts by weight of said 4- bromo-3 -chlorodiphenyl ether.

5. A composition consisting essentially of l00 parts by weight of 4-bromo-3-chlorodiphenyl ether, about 100 parts by weight of chlorinated biphenyl having about 32 percent by weight chlorine, about 43 parts by weight of dibromoethylbenzene and about 43 parts by weight of 3-chlorodiphenyl ether. 

2. A composition of claim 1 where the monohalogenated diphenyl ether is 3-chlorodiphenyl ether.
 3. A composition of claim 1 where the monohalogenated diphenyl ether is 3-bromodiphenyl ether.
 4. A composition consisting essentially of 4-bromo-3-chlorodiphenyl ether and 3-chlorodiphenyl ether wherein said 3-chlorodiphenyl ether is present in amounts of from about 17 to about 33 parts by weight per 100 parts by weight of said 4-bromo-3''-chlorodiphenyl ether.
 5. A composition consisting essentially of 100 parts by weight of 4-bromo-3''-chlorodiphenyl ether, about 100 parts by weight of chlorinated biphenyl having about 32 percent by weight chlorine, about 43 parts by weight of dibromoethylbenzene and about 43 parts by weight of 3-chlorodiphenyl ether. 